In any process where liquids of different densities form an emulsion as a part of the process, it is often desirable and economical to break the emulsion for possible reuse of one or more of the liquid components. The emulsion breaking process is exemplified by its wide use in the petroleum industry. Here, as a result of either the producing or refining steps of a crude product, it is not only desirable, but sometimes necessary to separate or break an emulsion compromised primarily of water and crude oil. Due to the different densities, oil ordinarily floats to the surface of the water segment.
For large scale operations, the separation procedure usually embodies a gravity separation in which the heavier water or aqueous solution will gravitate to the bottom of a holding tank or receptacle. As the lighter hydrocarbon component rises to the water's surface it can be skimmed off or otherwise removed.
Toward assuring an efficient and continuous emulsion breaking operation, the separating tank is usually provided with means for adjusting the flow rate of the crude or separated oil, to assure a degree of continuity in flow through.
The separation or emulsion breaking process finds particular relevance in the offshore petroleum industry where it is essential to separate the crude product from produced water. An environmental mandate followed by the industry is to dispose of produced water back into the surrounding body of water without causing pollution to the latter. Alternately, the produced water can be disposed of by underground injection. In either instance the produced water must be free of all traces of crude oil if federal and state regulations are to be complied with.
Toward achieving an efficient emulsion separation process and to illustrate the invention, there is hereinafter disclosed a water-oil separation facility for treating or breaking an emulsion comprised primarily of water or an aqueous solution, together with a crude oil segment. The emulsion tank receives a continuous flow of the emulsion, preferably at an inlet adjacent to the tank's floor. Physical separation of the crude oil from the water will be essentially a gravity flow. Thus, the lighter oil component will slowly gravitate toward the surface of the relatively quiescent body of water. Chemicals can be added to the emulsion to accelerate the separation process.
The top of the emulsion-holding tank interior wall is provided with an overflow trough which embodies a skimming weir. This trough encircles the tank at an elevation such that the thin floating layer of oil will overflow into the skimming weir. Thereafter the oil is discharged from the trough to a collection point or to a storage tank.
Separated water is conducted from the tank into a flow control system comprised primarily of a pair of water legs cooperative with a weir box. The weir box is fitted with an adjustable overflow weir cap to control and maintain water in the tank at a desired level. Valving in the water overflow system is operable to regulate the flow of emulsion through the tank.
It is therefore a primary object of the invention to provide an effective and efficient water-oil separation system for breaking an emulsion comprised of liquids of differing densities and specific gravities.